Recently, as a method for transmitting a signal between a plurality of devices at high speed, millimeter-wave communication using millimeter waves as carrier waves has become widespread. For example, millimeter-wave communication is used to transmit an interface signal in a detachable computer which detachably connects a tablet terminal and a keyboard. Some detachable computers can be selectively used as a notebook computer and a tablet computer by attaching one of the tablet terminal and the keyboard in reverse.
In millimeter-wave communication, the distance between a transmitting antenna for transmitting a signal and a receiving antenna for receiving a signal must be short to realize high-speed signal transmission because of the characteristics of millimeter waves. When millimeter-wave communication is used to transmit the interface signal between the tablet terminal and the keyboard in the detachable computer, the transmitting and receiving antennae for transmitting and receiving the interface signal are provided in both the tablet terminal and the keyboard within a distance in which high-speed signal transmission can be realized by millimeter-wave communication.
However, as described above, in the detachable computer, one of the tablet terminal and the keyboard may be reversed and connected. In this case, the transmitting and receiving antennae in the tablet terminal may be located away from those in the keyboard in a manner that the transmitting or receiving antenna in the tablet terminal cannot maintain the distance for realizing high-speed signal transmission in accordance with millimeter-wave communication with that in the keyboard. Thus, at least one of the tablet terminal and the keyboard comprises transmitting and receiving antennae used in a normal connection state, and transmitting and receiving antennae used in a reverse connection state. In this structure, even when one of the tablet terminal and the keyboard is reversed, the transmitting and receiving antennae provided in the tablet terminal and the keyboard can be located within a distance in which high-speed signal transmission can be realized in accordance with millimeter-wave communication. However, this structure increases the cost for producing the tablet terminal and the keyboard.
New technology is needed to solve the above problem.